Compact size plunger pump

Abstract

An ink liquid supply system for an ink jet system printer includes an ink liquid reservoir for containing ink liquid therein, and a compact size plunger pump for supplying the ink liquid to a nozzle. The compact size plunger pump integrally includes three pressure chambers defined by coaxially connected pistons. The pistons are driven to reciprocate by a plunger associated with an electro-magnetic solenoid. The first pressure chamber functions to introduce the ink liquid from the ink liquid reservoir and develop the ink liquid toward the nozzle. The third pressure chamber functions to introduce an ink liquid collected by a beam gutter of the ink jet system printer for returning the ink liquid to the ink liquid reservoir. The second pressure chamber functions as a damper for decelerating the shift movement of the pistons and plunger, thereby reducing the shock which will be created when the plunger is attracted by the electromagnetic solenoid.

What is claimed is: 
     
       1. A compact size plunger pump comprising: a first cylinder block;   a first piston disposed in said first cylinder block for determining a first pressure chamber, said first pressure chamber introducing a liquid from a reservoir and developing the liquid at a constant flow rate;   a second cylinder block coaxially connected to said first cylinder block;   a second piston coaxially connected to said first piston, said second piston being disposed in said second cylinder block for determining a second pressure chamber, wherein the volume of said second pressure chamber is greater than the volume of said first pressure chamber;   a plunger coaxially connected to said second piston for reciprocating said first and second pistons within said first and second cylinder blocks;   an electromagnetic solenoid for attracting said plunger in a predetermined direction; and   communicating means for directly communicating said second pressure chamber to said reservoir through a thin opening which permits bi-directional liquid fluid flow so that during a pump intake stroke the liquid is filled in said second pressure chamber and a fluid resistance is created at said thin opening, thereby decelerating the reciprocating movement of said plunger and said first and second pistons.   
     
     
       2. An ink liquid supply system for an ink jet system printer, said ink jet system printer comprising a nozzle for emitting an ink liquid supplied from said ink liquid supply system and a beam gutter for collecting waste ink droplets emitted from said nozzle and for recovering the waste ink liquid toward said ink liquid supply system, said ink liquid supply system comprising: an ink liquid reservoir for containing the liquid therein; and a compact size plunger pump comprising: a cylinder block;   a first piston disposed in said cylinder block for determining a first pressure chamber;   a second piston coaxially connected to said first piston and disposed in said cylinder block for determining a second pressure chamber and a third pressure chamber, wherein the volume of said second pressure chamber is greater than the volume of said first pressure chamber;   a plunger connected to said second piston for reciprocating said first and second pistons;   an electro-magnetic solenoid for attracting said plunger in a predetermined direction;   a first inlet valve for introducing the ink liquid from said ink liquid reservoir to said first pressure chamber;   a first output valve for developing the ink liquid from said first pressure chamber toward said nozzle;   a thin opening formed in said cylinder block for directly communicating said second pressure chamber with said ink liquid reservoir for introducing ink liquid into said second pressure chamber during a pump intake stroke and for outputting ink liquid from said second pressure chamber during a pump compression stroke with a substantial fluid resistance;   a second inlet valve introducing the waste ink liquid from said beam gutter to said third pressure chamber; and   a second outlet valve for returning the waste ink liquid from said third pressure chamber to said ink liquid reservoir.